NEW YORK -- The increased demand for "green" vehicles is spilling over to the rental car counter, where many more drivers will soon be able to chose a hybrid vehicle.

Hertz Global Holdings Inc. said Thursday it will spend $68 million to add 3,400 Toyota Prius hybrids to its fleets by 2008. And Avis Budget Group Inc. said this week it plans to make 1,000 hybrid Prius vehicles available for rent as early as next week.

Brian Chee, an automotive analyst for Autobytel.com's soon to be launched Web site MyRide.com, said that even with the fleet expansions, hybrid vehicles still represent a small part of rental car fleets.

"This is a first step," Chee said. "It'll be interesting to see if the rental car companies continue this. Like other companies, they're making a 'green' statement, and this is a good way to do it."

By replacing 1,000 of its ordinary rental cars with the gas-electric Prius models, Hertz said it will reduce carbon dioxide emissions by an estimated 3,000 tons per year.

"Today's announcement highlights the next step in what is already a multiyear effort by Hertz to promote environmental sustainability throughout the company," Mark Frissora, the company's chairman and chief executive, said at Thursday's announcement.

Hertz said its hybrid vehicles will be available for rent at 50 of the company's U.S. airport locations, with 100 of them reserved for its New York City fleet.

The stop-and-go flow of Manhattan traffic provides an ideal driving environment for the hybrids, allowing them to mainly operate off of their electric motors, the company said.

New York Mayor Michael Bloomberg said the greater availability of hybrid rental cars is in line with his city's goal to reduce its emissions by 30 percent by the year 2030.

"These hybrid cars really put Hertz in the driver's seat ... in meeting one of the greatest challenges of our time, which is global warming," Bloomberg told the gathering at the Museum of Natural History.

John Barrows, a spokesman for Avis, said this week his company will offer Prius hybrids in its California, Portland, Ore., Seattle and Washington, D.C., markets but may expand the locations in the future based on consumer demand.

Barrows said Avis also believes that the Prius rentals will not only appeal to travelers, but those interested in buying a hybrid.

"Obviously we have customers who want them," he said. "And there are other people out there who are interested in purchasing a hybrid but really want to check one out before buying one."

Chee, the automotive analyst, said the rentals offer Toyota Motor Corp. a chance to showcase the Prius, as well as give potential buyers a chance to decide if a hybrid is right for them.

"I do think it's a risky move for Toyota, because what they're saying is: 'Here's the car, here's how it drives, we stand by our power train, and we think it'll win people over,'" Chee said.

"It shows Toyota's confidence that it'll win over fans when they don't have to buy it."

Enterprise Rent-A-Car also operates a fleet of more than 3,000 hybrid vehicles, in addition to 41,000 flex-fuel cars and light trucks that can run on ethanol-based fuel, the company said.